Create A/B test of SDCH

To do this, I needed to add the feature that ALL FieldTrials that are
established in the browser process are forwarded and established in
the corresponding renderer processes.  This then allows both DNS impact,
 as well as SDCH inmpact (and any other field tests) to be studied
at the same time in a single binary.

This checkin also establishes a pattern that when we're doing A/B tests
via a histogram such as RequestToFinish, that we produce names for
all groups, rather than leaving one group as the "default" or "empty postfix"
group.  This is critical for naming various sub-groups when a multitude
of tests are taking place at the same time.

BUG=15479

r=mbelshe
Review URL: http://codereview.chromium.org/150087

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19595 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 22 insertions, 4 deletions

diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 2fad6fb..5b33bd2 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -1326,7 +1326,7 @@ void RenderView::DidReceiveTitle(WebView* webview,
 void RenderView::DidFinishLoadForFrame(WebView* webview, WebFrame* frame) {
   WebDataSource* ds = frame->GetDataSource();
   NavigationState* navigation_state = NavigationState::FromDataSource(ds);
-  // TODO(darin): It should not be possible for navigation_state to be null 
+  // TODO(darin): It should not be possible for navigation_state to be null
   // here!
   if (navigation_state)
     navigation_state->set_finish_load_time(Time::Now());
@@ -1344,7 +1344,7 @@ void RenderView::DidFinishDocumentLoadForFrame(WebView* webview,
                                                WebFrame* frame) {
   WebDataSource* ds = frame->GetDataSource();
   NavigationState* navigation_state = NavigationState::FromDataSource(ds);
-  // TODO(darin): It should not be possible for navigation_state to be null 
+  // TODO(darin): It should not be possible for navigation_state to be null
   // here!
   if (navigation_state)
     navigation_state->set_finish_document_load_time(Time::Now());
@@ -2894,10 +2894,28 @@ void RenderView::DumpLoadHistograms() const {
 
   UMA_HISTOGRAM_MEDIUM_TIMES("Renderer4.BeginToCommit", commit - begin);
   UMA_HISTOGRAM_MEDIUM_TIMES("Renderer4.BeginToFinishDoc", finish_doc - begin);
+
+  static const TimeDelta kBeginToFinishMin(TimeDelta::FromMilliseconds(10));
+  static const TimeDelta kBeginToFinishMax(TimeDelta::FromMinutes(10));
+  static const size_t kBeginToFinishBucketCount(100);
+
+  UMA_HISTOGRAM_CUSTOM_TIMES("Renderer4.BeginToFinish",
+      finish - begin, kBeginToFinishMin,
+      kBeginToFinishMax, kBeginToFinishBucketCount);
+
+  DCHECK(FieldTrialList::Find("DnsImpact") &&
+         !FieldTrialList::Find("DnsImpact")->group_name().empty());
   UMA_HISTOGRAM_CUSTOM_TIMES(
       FieldTrial::MakeName("Renderer4.BeginToFinish", "DnsImpact").data(),
-      finish - begin, TimeDelta::FromMilliseconds(10),
-      TimeDelta::FromMinutes(10), 100);
+      finish - begin, kBeginToFinishMin,
+      kBeginToFinishMax, kBeginToFinishBucketCount);
+
+  DCHECK(FieldTrialList::Find("GlobalSdch") &&
+         !FieldTrialList::Find("GlobalSdch")->group_name().empty());
+  UMA_HISTOGRAM_CUSTOM_TIMES(
+      FieldTrial::MakeName("Renderer4.BeginToFinish", "GlobalSdch").data(),
+      finish - begin, kBeginToFinishMin,
+      kBeginToFinishMax, kBeginToFinishBucketCount);
 
   UMA_HISTOGRAM_MEDIUM_TIMES("Renderer4.CommitToFinish", finish - commit);